<!DOCTYPE html>
<html>
<head>
   <meta name="viewport" content="initial-scale=1, viewport-fit=cover">
   <title>Designing Websites for iPhone X: Respecting the safe areas</title>
   <style>        * {
       padding: 0;
       margin: 0;
   }
   html, body {
       height: 100%;
   }
   body {
       padding-top: constant(safe-area-inset-top);
       padding-left: constant(safe-area-inset-left);
       padding-right: constant(safe-area-inset-right);
       padding-bottom: constant(safe-area-inset-bottom);
   }
   .content {
       background: -webkit-gradient(linear, 0 0, 0 bottom, from(#ffd54f), to(#ffaa22));
       width: 100%;
       height: 724px;
   }    
   </style>
</head>
<body>
<div class="content">this is subElement</div>
</body>
</html>